[BigJim]

Without going back and reading all the posts, let me ask this: with your setup, the entire original shaft rotates, which originally didn't, correct? The original shaft did not rotate but slid in and out with the locking set bolt riding in the slot. A couple of questions, first of all, if the shaft were to stop and need to be locked, with the head of the locking bolt that usually rides in the slot just slightly on the edge of that slot, wouldn't it, or could it, mar the edge of that slot where it would or could hamper the smooth transition in and out of the shaft?

Second, what stops the shaft, when the threads come to where usually the locking bolt head in the slot stops the travel? You sure don't want to lock down on the threads. Forgive me as I just woke up from my SS nap, as I was practicing how to sleep before I went to sleep. lol
OK one more question, how much travel does the ram have now? Is it the same as before as I picture it is?

 

[BigJim]

BigJim;

The threaded ram does rotate with this modification. The 7/16" dia. bolt I settled on for the mod is 3-5/16" long (head included) with 1-1/4" of thread and 1-3/4" of shoulder. I chose a 20tpi pitch for better grip and less play. I experimented with quite a few different bolt lengths and thread to shoulder "ratios". This length of threading (1-1/4") when screwed all the way into the back of the ram assures the ram's outward travel stops just before the threads come under the locking screw/pin.

Overall ram travel is controlled by turning the cranking wheel (now sticking out of the rear of the tailstock) all the way in or all the way out. Of course most of the time tightening down on a piece wood for turning will stop somewhere in between the extremes.

On my lathe there is approx. 1-3/4 to 1-7/8 inches of tailstock spindle travel. Since the ram can "stop" conceivably anywhere after snugging down your project the locking screw/pin is simply tightened down at that point on the surface of the ram...the non-threaded part.

If it appears that the locking pin is going to land on either edge of the slot just turn the crank a hair more forward to either put the pin directly in the slot or rotate it a hair more in the tightening direction to move it away from that edge of the slot. The wood being turned should be able to take a smidge of extra squeeze between the centers if needed to accomplish this.

I added a few pics below to show the general configuration and the bolt I used for the mod...pardon the clutter in one of them. The first picture shows the threads tapped into the ram where the crank screws into it.
View attachment 425281
View attachment 425279 View attachment 425280
Close ups of the cranking wheel.
View attachment 425282 View attachment 425283

I hope I've answered your questions and if you have more please ask.

Biznawich
Bruce Jennings

I really appreciate you taking the time to explain this, thank you. It does make good sense and I do see how it all works now. One thing I would want in a tail stock with an adjusting wheel would be for drilling a center hole in my work piece. Maybe somewhere someone makes a tail stock that can be adjusted on the tube shaft using a wheel to move it back and forth, like the teeth on a drill press to adjust the table up or down. That would be ideal for drilling center holes of any depth, not just the travel of the ram of the tail stock. Just a thought. I appreciate your time and effort to explain all of this.

 

[BigJim]

Bill, I appreciate it but I have another lathe just like the one I have now. Thanks for the heads up buddy.

 

[BigJim]

They look like parts of C clamps.

 

[BigJim]

Thanks for the information Biz, I appreciate it.